Hmm I’m seeing the opposite. The last graph shows Google’s hash table outperforming in all but a few places, including at 400k. Perhaps you mixed the axes up, lower is better here.

I also just want to comment that skepticism to high claims is good but your comment seems a bit too harsh. Briefly looking at his post where he goes into his “fastest hash table” it’s quite long, very detailed and has similar graphs. That doesn’t seem under-researched to me.